1. Field of Invention
The present invention relates to collision avoidance systems, and more specifically to an ultrasonic system used on vehicles.
2. Description of Prior Art
In the course of operating a motor vehicle safely at varying speeds it is necessary for the operator of the vehicle to gather information concerning traffic conditions to make sound driving decisions. Information obtained, such as the known proximity of potentially dangerous objects and their associated relative velocities requires mental processing for the operator to make sound driving decisions, such as whether or not there is enough time, or if it is clear, to change lanes, or to stop. The information must be gathered from an area which effectively spans 360 degrees.
In order to gather information from this area the operator is required to physically turn, such as one would do when checking a blind spot. In doing so, the forward progress of the vehicle continues unchecked.
Heretofore several ultrasonic devices have been proposed for assisting the operator in gathering traffic information regarding areas that cannot be viewed easily, such as the blind spot, which is common to all mirrors.
U.S. Pat. No. 3,681,750 to Larka (1972) discloses a passive device which detects ultrasonic signals; however, this device merely detects the presence of moving objects and does not inform the operator of the distance to these objects nor of their velocity, relative to the vehicle. This greatly inhibits the operator's ability to make sound driving decisions. Also, several devices are required to scan all pertinent areas.
Several types of ultrasonic collision avoidance systems have been proposed in, for example, U.S. Pat. Nos. 3,802,397 to Sindle (1974), 4,240,152 to Duncan and Wiley (1980), 4,260,980 to Bates (1981), 4,442,512 to Sigeeyuki and Akite (1980), 4,450,430 to Barishpolsky (1980), 4,626,850 to Chey (1986), and 4,694,295 to Miller and Pitton (1987). All of these systems have certain factors in common.
a) All require numerous transducers along with associated circuitry to scan pertinent areas. This greatly increases the cost of the system. Also, use of multiple transducers increases the complexity of the system, thereby decreasing dependability.
b) All utilize transducers mounted in a way that the emitted ultrasonic signal is perpendicular to the vehicle. This arrangement does not make effective use of the natural shape of the signal since, at very close distances, the width of the signal is very narrow as opposed to having a much larger width at greater distances. As a consequence of this arrangement, multiple transducers are needed in order to scan the entire side of the vehicle.
c) All require separate mountings for each transducer to scan an individual area. Transducers which are located at different points on the vehicle requires great lengths of cable to interconnect and coordinate their activities, creating logistical and design problems.
d) All are unable to differentiate between a stationary object and one that is moving. Stationary objects create false warnings which hinder rather than assist the operator.
e) Their operation merely warns of objects when they are detected within a certain fixed distance. They do not compensate for varying vehicle speeds, which necessarily dictate a greater warning distance.
f) Their operation merely detects the presence of objects and does not calculate the object's relative speed with respect to the vehicle. The relative speed could be used to predict if a lane change could be accomplished safely, in time, before the object arrives in the "safe" zone. This would eliminate the tedious task of guessing if a lane change could be accomplished safely.
g) All are unable to compensate for the addition of a trailer which would effectively void any protection provided by the system since any object located adjacent the trailer would go undetected. Also, the trailer itself would cause a false warning since the transducer used to scan the rear area, if provided, would detect the reflected ultrasonic signal from the trailer.
h) All are unable to compensate for the various blind spots of different operators of the vehicle. Each operator has his or her own blind spot, which is directly related to that person's stature. Therefore, a system which was designed for one specific operator would be useless for another.
i) All are unable to provide protection against would-be thieves when the vehicle is left unattended.
j) All utilize dedicated electrical circuits which do not allow for an operator to program in preferred warning distances.
k) All lack capability for altering the position of the side mirror so that the object which has been detected to be in the blind spot can be in full view of the operator.
l) All are unable to detect the presence of a new driver in order to automatically adjust the mirror position to the new driver's preferred position.
As will be described hereinafter, the ultrasonic system of the present invention meets these requirements by providing structure which is capable of receiving and assimilating information, processing same, making decisions and warning the operator of the vehicle of the possibility of collision in time to avoid same.